1. Field of the Invention
The present invention relates to a washing machine, and more particularly to a steam generating device, which generates steam to be supplied to a washing machine, and a washing machine having the steam generating device.
2. Discussion of the Related Art
Generally, washing machines are classified into a pulsator type, in which a washing operation is carried out using a flow of water generated in accordance with the rotation of a pulsator, and a drum type, in which a washing operation is carried out using the heads of wash water and laundry falling down in a horizontally-installed drum and frictional force generated between the drum and the laundry during rotation of the drum.
Recently, a washing machine, which has a function capable of washing laundry using steam, has been proposed. When steam is used in a washing operation, as in such a washing machine, it is possible to reduce the consumption of water and electricity, to achieve an enhancement in washing performance, to remove creases and odor, and to prevent generation of static electricity.
A drum washing machine, which performs a washing operation, etc., using steam, will be described hereinafter with reference to FIG. 1.
The drum washing machine includes a cabinet 10 forming an appearance of the washing machine, a cylindrical tub 20 horizontally supported by the cabinet 10 in the interior of the cabinet 10, to store wash water, a drum 30 rotatably installed in the tub 20, and a drive motor (not shown) for driving the drum 30. An inlet 13 is formed at a front side of the cabinet 10. The inlet 13 communicates with the interior of the drum 30 so that laundry can be put into or taken out of the drum 30 through the inlet 13. A door 11 is mounted to the inlet 13, to open or close the inlet 13. Water supply valves 15 are provided at one side of the drum washing machine. The water supply valves 15 are connected to external water pipes (not shown), respectively, so as to supply water to the tub 20. The water valves 15 are connected to a detergent box 27 via a hot water pipe 25a and a cold water pipe 26, respectively.
The drum washing machine also includes a steam generating device 50 for supplying steam to the drum 30. A water supply hose 25 and a steam hose 53 are connected to the steam generating device 50. The water supply hose 25 supplies water to the steam generating device 50, whereas the steam hose 53 supplies steam generated from the steam generating device 50 to the drum 30. Typically, the water supply hose 25 is connected to a hot water side of the water supply valve 15. The steam hose 53 has an end preferably having a nozzle shape, so as to effectively spray steam into the drum 30. Preferably, the steam hose 53 is installed such that the nozzle-shaped end thereof, from which steam is discharged, is exposed to the interior of the tub 20.
The configuration of the steam generating device 50 will be described in more detail with reference to FIGS. 2 and 3.
The steam generating device 50 includes a case 80. The case 80 includes a lower housing 81 forming an appearance of the steam generating device 50 and an upper housing 82 coupled to an upper end of the lower housing 81. A space for storing water is defined in the lower housing 81. The steam generating device 50 also includes a heater 55 for heating water stored in the case 80.
A water supply port 52b is formed at one side of the housing 82. The water supply port 52b is connected to the water supply hose 25, to introduce water from the water support hose 25 into the steam generating device 50. A steam discharge port 52a is formed at the other side of the housing 82. The steam discharge port 52a is connected to the steam hose 53, to supply steam from the steam hose 53 to the drum 20.
The heater 55 is installed on the bottom of the upper housing 82 such that it is completely submerged under water when water is introduced into the steam generating device 50. Thus, the heater 55 operates in a state of being submerged under water. To this end, a water level sensor 60 is installed at one side of the upper housing 82, to sense a water level of the steam generating device. Since the water level sensor 60 measures the level of water stored in the steam generating device 50, the amount of water stored in the steam generating device can be maintained at an appropriate level. That is, when the water level of the steam generating device 50 is lower than a first reference value (low water level), the water supply valve 15 is opened to supplement water. On the other hand, when the water level of the steam generating device 50 reaches a second reference (high water level), the water supply valve 15 is closed. In this case, the heater 55 operates to generate steam.
A temperature sensor 57 is also installed to measure the temperature of water heated by the heater 55 and the temperature of steam generated in accordance with the heating operation of the heater 55. The temperature sensor 57 measures the internal temperature of the steam generating device, in order to cut off the supply of electricity to the heater 55 when the measured temperature is higher than a reference value, and thus to prevent the heater 55 from being over-heated.
Hereinafter, the water level sensor 60 will be described in detail.
The water level sensor 60 includes a receptacle housing 61 forming an appearance of the water level sensor 60. The receptacle housing 61 is fixedly mounted to the steam generating device 50. The water level sensor 60 also includes electrodes arranged in the receptacle housing 61 such that they extend downwardly, to sense the level of water stored in the steam generating device 50. The electrodes 62, 63, and 64 are positioned at predetermined levels from the bottom of the lower housing 81, in order to sense the level of water stored in the steam generating device 50. The electrodes comprise at least a common electrode 62 functioning as a reference electrode for sensing a water level, a low-water-level electrode 63 for sensing a low water level, and a high-water-level electrode 64 for sensing a high water level. The common electrode 62 preferably has a length equal to or longer than the length of the low-water-level electrode 63.
Meanwhile, there is a possibility that, when water supplied through the water supply port 52b is splashed, and attached to the electrodes 62, 63, and 64, the water level sensor 60 may malfunction. Furthermore, it is difficult to completely prevent generation of vibration during operation of the washing machine. For this reason, the steam generating device 50 may also vibrate during operation of the washing machine, so that the water stored in the steam generating device 50 may roll.
Due to the above-mentioned factors, the water level sensor 60 may malfunctions. In order to prevent the water level sensor 60 from malfunctioning, a receptacle 70 is provided. The receptacle 70 is configured to enclose the electrodes 62, 63, and 64, and to have an open bottom. The receptacle 70 also preferably has an opening 70s. 
However, the above-mentioned conventional steam generating device and the washing machine equipped with the same have the following problems.
Since the conventional steam generating device has a substantially rectangular shape having a small height L1 and a large width L2, as shown in FIG. 4, it is difficult to install the steam generating device 50 in the washing machine. This is because, although the steam generating device 50 is typically installed in an upper portion of the washing machine, in detail, in a space defined between the cabinet 10 and the tub 20, the space between the tub 20 and the steam generating device 50 is relatively small.
In the space defined between the cabinet 10 and tub 20, a valve, hanging springs, etc. are also installed. For this reason, the space for installing the steam generating device 50 may be insufficient. As a result, it is difficult to install and repair the steam generating device 50.
Furthermore, although the steam generating device 50 is in an installed state, the steam generating device 50 may interfere with other elements of the washing machine when the washing machine is moved because the spacing t between the steam generating device 50 and the tub 20. As a result, the steam generating device 50 may be damaged. Since the spacing t between the steam generating device 50 and the tub 20 is relatively small, they may strike against each other due to vibrations generated during operation of the washing machine. As a result, the steam generating device 50 may be damaged.
In addition, it is required to enhance the performance of the steam generating device 50, for example, the amount of water used, energy efficiency, steam generating time, security, etc.
Meanwhile, when water boils in accordance with the operation of the steam generating device 50, air bubbles are abruptly generated. The generated air bubbles may be attached to the electrodes 62, 63, and 64, thereby causing the water level sensor 60 to malfunction.